Short Answer
Soffit is the material installed beneath roof overhangs. It can contribute to appearance, protection, and ventilation.
Detailed Explanation
Soffit is the underside of the roof overhang — the horizontal surface you see when you look up at the underside of the eave. It serves multiple functions: it provides a finished appearance by enclosing the underside of the roof overhang, it protects the roof framing and attic from weather and pest entry, and — when perforated or vented — it serves as intake ventilation for the attic. Vented soffit is one of the most common and effective forms of intake ventilation, allowing cool outside air to enter the attic space to replace warm air that exits through exhaust vents. Soffit can be made from vinyl, aluminum, wood, or fiber cement, with vinyl and aluminum being the most common on modern homes.
Why It Matters
Soffit is both a protective enclosure and a critical ventilation component. Its condition affects both appearance and attic ventilation performance.